Device to sharpen twist drills



June 13, 1950 J GANZ 2,511,055

DEVICE T0 SHARPEN TWIST DRILLS Filed April 15, 1946 s Sheets-Sheet 1 June 13, 1950 J. GANZ DEVICE T0 SHARPEN TwIsT DRILLS 3 Sheets-Sheet 2 Filed April 13, 1946 m F g-7 IIIIHMMMMMMI June 13, 1950 J. GANZ 2,511,055

DEVICE TO SHARPEN TWIST DRILLS Filed April 13,- 1946 3 Sheets-Sheet 3 Patented June 13, 1950 UNITED STATES PATENT OFFICE ApfplicationApril 13, 1946, Serial No. 661,938. In Switzerland April '13, 1945 3 Claims 1 The present invention relates to a new; and improved device for sharpening twist drills by grinding.

The; main, object of the invention consists in the provision of a device, by means of which the points of twist drills may be re-sharpened even by unexperienced workmenv in such a manner that the cutting, edges are truly symmetricaily arranged with reference to the axisof the twist drill and that the backing-off is effected in a predetermined measure.

In the accompanying drawings an embodiment of" my invention is shown byway ofan example.

Fig. 1' shows part of the twist-drill-grinding machine in a perspective view.

Fig. 2 is a side elevation of" the device seen in the direction of the arrow A part being shown in section on line III'I of Fig. 4.

Fig. 3 illustrates part of the device in a side elevation.

Fig. 4 is a cross-section taken on line I-V-IV of Fig. 2;.

Fig. 5 shows parts of the device in a top view parts being shown in section on line V--'V- of Fig. 2.

Figs. 6', '7 and 8' are cross-sections taken on lines of Fig. 5, on line VII-VII of Fig. 4 and on line VHI'VIII'of Fig; Brespectively.

Fig. 9 shows in a side elevation a clamp to hold the drill.

Fig. 10- illustrates the position of the tip of the drill with reference to the grinding disk while it is in its grinding position.

Fig: 1 1' is a face viewof the drill and of the shield controlling the position of the drill.

Figs. 12' and- 13- are faceviews ofthe drill arranged in its holder.

Fig. 14 is a section taken on line XIVXIV of Fig. 2.

The same numbers of reference relate to like partsin all the figures.

In the base of an electric motor l driving the grinding disk 2, a bar 4 is arranged running parallel with reference to the drivin shaft 3 of the motor I. On the bar 4 a device is adiustably mounted for holding" and guiding the twist drill B which is to be re-sharpen-ed on the cylindrical working face F of the grinding'disk'l. Said device comprises an arm 5 mounted on said bar 4. The arm 5 is fixed in its working position by a hand operated. clamping screw 6. Thefree end of arm 5 isprovided on eachside with a groove i; said grooves, running parallel to each other in a direction at a right angle to the shaft 3. The bottom. wall. of the grooves; lis provided. with a slot. 8. extending transversely through the, arm 5. In one of the saidgrooves 'l' a slide 1 I is arranged 2 slidabl'y: adjustably, said slide ll may be oper: ated and adjusted in its position by a screw threaded spindle 9' with an operating knob Ill. The slide ll may be fixed in its position. in the arm 5 by: a. nut I2 on a pin l l l extending through the-slots;

The slide H is carried on one end of the cylindrical pin lit the other end of which carries a device for truing the working face F of the disk 2. A collar formed integrally on the pin 1 l 1 between the ends: thereof is slidably seated in the other groove 1 on the arm 5 as shown in Figs. 3, 4 and '1'. As shown in: Fig. 7 the collar has twoflat faces preventing a rotation of the pin l l I in the groove 1. The device and its operation is known per se and is not shown in the drawings. On the slide H a sleeve 13 is arranged in which an upright trunnion I 4 is rotatably mounted. On the trunniOn I 4 a head" piece I5 is fastened in which a shorthorizontal shaft l-lll is rotatably mounted. The shaft l- 6l carries at its face a conical pin I! which serves to aid the adjustment of the head piece- I5 with reference to the working face F ofthe-grindi'ng disk 2*. To the shaft l e-l an angular-connecting piece I6 is fastened which carries abar 18 The: axis Z-Z of the bar I8 is at an obtuse angle with reference to the axis Y-Y of the shaft 1 61:. The bar 18' may be turned about its axisZZ-, in the angular connecting piece 16 and may be fixed in its: position by a set screw 56. The adjusting of the axis of the bar llland therewith of the cutting edges of the twist drill with referenceto the working face F of the grinding disk 2 is illustrated in Figs. 12*and 13. The angle over which the bar I 8 may be turned may be limited by a stud 22 (Fig. 8') to obviate any damaging of the adjusting device by the grinding disk 2-. In the bar it a longitudinal groove-23' is provided adapted to receive the drill to be sharpened. The groove 23is formed bytwo walls 24, 25'standing at an angle to each other the line of intersection of the walls 2 3 25 bein in the axis of the bar I8 On the bar 18' an annular slide 20 is adjustabl'y" mounted. The slide Z'limay be fixed on thebar k8- by means ofgripping members 26 pressed on the bar tB by means of a nut 2-1: having a conical face. The slide 263 is provided with a screw-threaded portion on which. a nut 32: is mounted, on which a coiled spring acts to take up the play. The nut 321s provided with an inwardly projecting: tooth 36 engaging an annular groove in aslid-e 34 which serves as an abutment for the drill? to be sharpened. The slide 34' engages the groove 23 of the bar 18.. The nut 32- servcs for the fine adjustment of the drillin its. axial direction, a marking 38= on the nutfacilita-tes the correct setting of the drill-abutment 32, 34 and therewith of the point of the drill with reference to the working face F of the grinding disk 2. The point of the conical pin H on the shaft l6l is used for adjusting the position of the drill with reference to the grinding face of the disk 2 as the latter is being reduced in diameter while doing work. At the inner end Of the bar I3 an abutment 4| is arranged engaging one of the flutes of the drill to secure the proper position of the cutting edges of the drill arranged in the groove 23 of the bar 18. The abutment 4! facilitates the positioning of the drill and its turning about 180 degrees to work the point of the drill quite symmetrically. The set screw 43 engaging a groove 46 of the pin l4 limits the movement of the bar 18 and therewith that of the point of the drill towards the working face of the grinding disk 2. By an adjustment of the set screw 43 the conicity of the point of the drill may be varied. To retain the drills, even those of small diameter, in the groove 23 of the bar ii; an auxiliary clamp 48 might be used. The clamp comprises a bar 49 and a blade spring 59 fixed together at one end. By means of a nut 51 and of a screw threaded bolt passing through bores of bar 49 and spring 50 the drill to be sharpened is held securely on the bar 18. The bar I8 is provided with a radial bore I8 suitably tapped for receiving a mounting pin 52 on the bar 49 (Figs. 1 and 9).

The use and operation of the device is as follows:

To sharpen a drill B the latter is placed into the groove 23 of the bar l8 and is secured therein by the clamp 48. The drill is arranged to abut on the member 4|. The drill being axially displaced by the adjusting device 20. The bar I8 is swung against the working face F of the grinding disk 2 about the axis of the trunnion [4, which movement is limited by the set screw 43 and the point of the drill is shaped first on one side by grinding, the bar I8 and therewith the drill being moved up and down about the axis 31-1}. If one side of the point of the drill B is ground to its proper shape the bar I8 with the drill B is moved away from the grinding face of the disk 2. The drill B is turned about 180 degrees about its axis and again fastened in the bar l8 whereupon the point of the drill B is again brought to bear on the working face F of the disk 2. The axes of all the drills of different diameters are all in a common plane SS (Figs. 12, 13) symmetrically to which the walls 24, 25 are placed. The plane SS is inclined at an angle a to the horizontal. The angle a is adjustable by loosening the set screw 55 and then rotatably adjusting the bar I 8 about the axis 2-2 after which adjustment the set screw 56 is again tightened. The angle a corresponds to the desired backing-off angle and is indicated by the scale 38. As shown in Figs. 11 and 12 for twist drills of any diameter the same angles are produced at a certain fixed position of the bar 18.

To attain full symmetrical faces of the point of the drill it is necessary that the drill be advanced equally towards the grinding disk in both of its grinding positions and that the drill be turned exactly 180 degrees.

What I wish to secure by U. S. Letters Patent is:

1. In a grinding device for twist drills, the combination, a grinding disc rotatable about a fixed axis and presenting a peripheral grinding face, a supporting bar arranged parallel to said fixed axis, a support carried by said bar and having thereon a slide adapted to be moved at right angles to said fixed axis, means for securing said slide in the desired position, a head piece rotatably mounted about a vertical axis on said slide, a horizontal shaft rotatably mounted in said head piece and provided at one end with an angular connecting piece to which is secured a drillreceiving bar in such a manner that the longitudinal axis of said bar forms an obtuse angle with said horizontal shaft, said drill receivin bar comprising a cylindrical rod having a longitudinal groove formed of angularly positioned plane walls for receiving the drill to be ground, said angular connecting piece being provided with means for rotatably adjusting said cylindrical rod with respect thereto, whereby the backing-off angle of the drill is changed, and means on said bar for positioning the end of the drill to be ground relative to the peripheral grinding face of said grinding disc.

2. In a grinding device for twist drills, the combination, a grinding disc rotatable about a fixed axis and presenting a peripheral grinding face, a supporting bar arranged parallel to said fixed axis, a laterally extending arm carried by said bar and having mounted on its outer edge a slide adapted to be moved at right angles to said fixed axis, means for securing said slide in the desired position, a head piece rotatably mounted about a vertical axis on said slide, means for limiting the rotative movement of said head piece to a predetermined and adjustable angle, a horizontal shaft rotatably mounted in said head piece and provided at one end with an angular connecting piece to which is secured a drill-receiving bar in such a manner that the longitudinal axis of said bar forms an obtuse angle with said horizontal shaft, means for limiting the rotative movement of said horizontal shaft to a predetermined angle, said drill receiving bar comprising a cylindrical rod having a longitudinal groove formed of angularly positioned plane walls for receiving the drill to be ground, said angular connecting piece being provided with means for rotatably adjusting said cylindrical rod with respect thereto, whereb the backing-01f angle of the drill may be changed, and means on said bar for positioning the end of the drill to be ground relative to the peripheral grinding face of said grinding disc.

3. A grinding device according to claim 1, in combination with a holder comprising a detachable clamping device adapted to retain the drill to be ground in the groove of said cylindrical rod, said holder including a bar for engaging said rod and a leaf spring engaging said drill and urging the same into said groove.

' JOSEPH GANZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 563,593 Hoenscheid July '7, 1896 643,703 White Feb. 20, 1900 751,198 Parpart Feb. 2,1904 1,195,248 Mallory Aug. 22, 1916 2,139,938 Dixon Dec. 13, 1928 2,356,175 Olson et a1. Aug. 22,1944 2,415,121 Wiken et al Feb. 4, 1947 FOREIGN PATENTS Number Country Date 9,930 Great Britain May 30, 1900 14,432 Great Britain June 19, 1909 

